The present invention relates generally to access needles of the type well-suited for percutaneous introduction into a body lumen and relates more particularly to a novel access needle that is well-suited for percutaneous implantation in a body lumen.
Certain patients are unable to take food and/or medications transorally due to an inability to swallow. Such an inability to swallow may be due to a variety of reasons, such as esophageal cancer, neurological impairment and the like. Although the intravenous administration of food and/or medications to such patients may be a viable short-term approach, it is not well-suited for the long-term. Accordingly, the most common approach to the long-term feeding of such patients involves gastrostomy, i.e., the creation of a feeding tract or stoma between the stomach and the upper abdominal wall. Feeding is then typically performed by administering food through a catheter or feeding tube that has been inserted into the feeding tract, with the distal end of the feeding tube extending into the stomach and being retained therein by an internal anchor or bolster and the proximal end of the feeding tube extending through the abdominal wall.
(For certain patients, it is desirable for food to be administered directly to the patient's jejunum, without first passing through the patient's stomach. In such cases, a jejunostomy is typically performed, a jejunostomy being similar to a gastrostomy, except that a jejunostomy results in the distal end of the feeding tube being implanted in the patient's jejunum, instead of in the patient's stomach.)
Although gastrostomies were first performed surgically, most gastrostomies are now performed using percutaneous endoscopy and result in the implantation of a catheter/bolster assembly (also commonly referred to as a percutaneous endoscopic gastrostomy (PEG) device) in the patient. Two of the more common techniques for implanting a PEG device in a patient are “the push method” (also known as “the Sacks-Vine method”) and “the pull method” (also known as “the Gauderer-Ponsky method”). Information regarding the foregoing two methods may be found in the following patents, all of which are incorporated herein by reference: U.S. Pat. No. 5,391,159, inventors Hirsch et al., which issued Feb. 21, 1995; U.S. Pat. No. 5,167,627, inventors Clegg et al., which issued Dec. 1, 1992; U.S. Pat. No. 5,112,310, inventor Grobe, which issued May 12, 1992; U.S. Pat. No. 4,900,306, inventors Quinn et al., which issued Feb. 13, 1990; and U.S. Pat. No. 4,861,334, inventor Nawaz, which issued Aug. 29, 1989.
According to the push method, the distal end of an endoscope is intubated (i.e., inserted) into a patient's mouth and is passed through the esophagus into the stomach. After distension of the stomach by inflation, an entry site on the abdomen is identified using the endoscope for transillumination, and an incision is made by passing the distal end of a needle coupled to an outer cannula through the abdominal and stomach walls and into the stomach. The proximal end of the outer cannula remains outside of the body and acts as a stop to prevent the proximal end of the needle from falling into the stomach. A snare is inserted into the stomach via the endoscope and is looped over the distal end of the needle. The snare is then “walked” up the needle until the outer cannula is snared. The snared cannula is then pulled proximally to tack the cannula to the stomach and, in turn, to secure the stomach wall to the abdominal wall. The needle is then removed while keeping the cannula in place. A first end of a flexible guidewire is then passed through the cannula and into the stomach where it is grasped by the snare, the second end of the guidewire remaining external to the patient. The endoscope and the snare are then withdrawn from the mouth of the patient to deliver the first end of the guidewire.
A push-type catheter implanting assembly is then inserted over the first end of the guidewire and is pushed over the guidewire towards its second end. The push-type catheter implanting assembly typically comprises a gastrostomy feeding tube, the gastrostomy feeding tube having a dome-shaped internal bolster disposed at its trailing end and having a tubular dilator serially connected to its leading end. The gastrostomy feeding tube and the internal bolster are typically made of a soft, biocompatible material, like silicone rubber, and may form a unitary structure. The dilator, which tapers in outer diameter from its trailing end to its leading end, is typically made of polyethylene or a like material which is stiffer than silicone but which still possesses some flexibility. Advancement of the push-type catheter implanting assembly over the guidewire continues until the front end of the dilator reaches the cannula and pushes the cannula out through the abdominal wall of the patient. The front end of the dilator is then pulled through the abdominal wall until the front end of the gastrostomy feeding tube emerges from the abdomen and, thereafter, the internal bolster at the rear end of the gastrostomy feeding tube engages the stomach wall. The guidewire is then removed from the patient. The clinician then re-intubates the patient with the endoscope and uses an optical channel in the endoscope to inspect whether the internal bolster is properly seated in the stomach.
If the internal bolster is properly placed against the stomach wall, a proximal portion of the implanted gastrostomy feeding tube is then typically cut and removed from the implanted tube to reduce the externally-extending portion of the tube to a desired length. (The removal of the proximal portion of the gastrostomy feeding tube also results in the removal of the dilator, which is connected thereto.) An external bolster is typically secured to the remaining implanted portion of the feeding tube to engage the abdomen in such a way as to prevent longitudinal movement of the feeding tube within the stoma tract. Additionally, a “Y-port” adapter is typically attached to the proximal end of the implanted feeding tube, the Y-port adapter being adapted to receive a pair of connector tips through which food and/or medications may be dispensed. In addition, a detachable locking clip is typically secured to the implanted feeding tube at a point between the external bolster and the Y-port adapter to prevent gastric fluids from escaping through the proximal end of the feeding tube when the feeding tube is not in use.
The pull method is similar in some respects to the above-described push method, the pull method differing from the push method in that, after the cannula is snared and the needle is removed therefrom, a first end of a suture is inserted through the cannula and into the stomach where it is grasped by the snare, the second end of the suture remaining external to the patient. The endoscope and the snare are then withdrawn from the mouth of the patient to deliver the first end of the suture. The first end of the suture is then coupled to the leading end of a pull-type catheter implanting assembly, the pull-type catheter implanting assembly typically comprising a gastrostomy feeding tube having an internal bolster at its trailing end and a plastic fitting at its leading end. The plastic fitting typically has a conical front portion that serves as a dilator, said conical front portion tapering in diameter from the leading end of the feeding tube to a front tip. A wire loop is fixed to the front tip of the plastic fitting, the first end of the suture being tied to the wire loop.
Using the second end of the suture, the pull-type catheter implanting assembly is then pulled retrograde through the patient until the gastrostomy feeding tube emerges from the abdomen of the patient and the internal bolster engages the stomach wall of the patient. Next, as is the case in the push method, the clinician then re-intubates the patient with the endoscope in order to visually inspect the placement of the internal bolster within the stomach. If the bolster is properly seated in the stomach, the implanted gastrostomy feeding tube is then typically cut to a desired length, an external bolster is typically secured to the cut implanted tube, a “Y-port” adapter is typically attached to the proximal end of the implanted feeding tube, and a detachable locking clip is typically secured to the implanted feeding tube at a point between the external bolster and the Y-port adapter.
Regardless of whether the push method or the pull method is used, an early part of the procedure involves using a needle/cannula assembly, also commonly referred to in the art as “an access needle.” As explained above, the access needle is used to make an incision through the abdominal and stomach walls of the patient. A snare is then looped over the distal end of the needle portion of the access needle and is “walked” up the needle portion until the cannula portion of the access needle is snared. The snared cannula portion is then pulled proximally to tack the cannula portion to the stomach and, in turn, to secure the stomach wall to the abdominal wall. The needle portion of the access needle is then removed while keeping the cannula portion in place, and the distal end of a suture or guidewire is inserted through the cannula portion and into the stomach in order to be grasped by the snare.
One type of access needle commonly employed in the above procedure comprises a solid metal needle (or stylet) removably mounted within a metal cannula. A plastic needle hub is fixed to the proximal end of the metal needle, and a plastic cannula hub is fixed to the proximal end of the metal cannula. The needle hub and the cannula hub are sized and shaped to permit a portion of the needle hub to be removably inserted into the cannula hub in such a way as to delimit insertion of the needle distally through the cannula. A tab is provided on the needle hub and a corresponding slot is provided on the cannula hub, said slot being adapted to receive said tab in order to permit said needle and said cannula to be placed in a particular rotational orientation relative to one another. The cannula hub is also shaped to include a lateral flange upon which a user may rest, for example, his forefinger and middle finger.
Another type of access needle commonly used in the above procedure comprises a hollow metal needle removably mounted within a plastic cannula. A plastic needle hub is fixed to the proximal end of the metal needle, and a plastic cannula hub is fixed to the proximal end of the plastic cannula. The needle hub and the cannula hub are sized and shaped to permit a portion of the needle hub to be removably inserted into the cannula hub in such a way as to delimit insertion of the needle distally through the cannula.
In both of the above-described access needles, the lengths of the needle and the cannula are such that, with the needle fully inserted into the cannula, only the needle tip extends distally beyond the distal end of the cannula.
One type of problem periodically encountered with access needles of the types described above is the premature withdrawal or “backing-out” of the distal end of the access needle from the patient. As explained above, after the access needle is inserted into the patient, a snare is typically looped over the distal end of the needle and “walked” up the needle until the surrounding cannula is securely snared. As can readily be appreciated, if, prior to the secure grasping of the cannula by the snare, the patient moves relative to the access needle, the distal end of the access needle may be withdrawn from the patient. Such a withdrawal or “back-out” of the access needle from the patient is highly undesirable because, on one hand, it is exceptionally difficult to re-insert the access needle into the same incision holes already made in the abdominal and stomach walls, and, on the other hand, it is undesirable to make more incisions in a patient than are minimally required. Moreover, regardless of whether the needle is reinserted into the same holes or is used to make new incision holes, the re-introduced access needle must be located by the endoscope and grasped by the snare, all of which can be time-consuming and laborious. As a result, in order to avoid needle “back-out,” it is not uncommon for a clinician other than the physician working the endoscope to hold the access needle securely against the skin of the patient until the cannula is fully snared. As can be appreciated, the involvement of a clinician in this manner means that an additional person is engaged in performing the procedure. The involvement of such an additional person is undesirable in that it increases the cost of performing the procedure and it makes more crowded the workspace in which the procedure is performed.
As can be appreciated, the above-described problem of access needle “back-out” is even greater where the access needle is used to perform percutaneous endoscopic jejunostomies since, in such a procedure, the needle must go deeper into tissue to locate the lumen of the jejunum and the procedure takes more skill to place the cannula.